Born in Walajapet, Tamil Nadu, Arun Karthik, made his first-class debut with his state side in 2008. He had a great beginning as he scored 149 opening the innings against Karnataka in their own backyard. He did fairly well throughout the season. He had a very good second season and ended the campaign as the second highest run-getter for Tamil Nadu. Since then, he has been a regular member of the side, although he was not left out for a few matches.

He played for Royal Challengers Bangalore from 2011 to 2013, but went unsold in the 2014 auctions. His most memorable moment with RCB is the six he hit off the last ball to help his side beat South Australian Redbacks in a game at the 011 Champions League T20.